1. Field of the Invention
This invention relates to surgical knot tying devices. In particular, the invention relates to knot tying devices suitable for forming knots in suture during endoscopic, e.g. arthroscopic, surgical procedures.
2. Description of the Prior Art
Repairing tissue during endoscopic surgical procedures often requires suturing the tissue. The suture is sometimes used alone to stitch together tears or reattach soft tissue to bone, etc., and sometimes used with anchors to tie tissue to a supporting surface. The suture is generally secured by tying the ends or legs in a knot which may be formed in a variety of styles and in a variety of ways. Clearly, knot tying in endoscopic procedures is more challenging than in open procedures because of the difficulty in manipulating suture legs in small spaces. Consequently, numerous devices have been developed to assist a surgeon.
Knots may be formed within the body (intracorporeally) or outside the body (extracorporeally). In either case, the formation of the knot requires significant manual manipulation of the suture legs to be tied. In the case of extracorporeal knots, the manipulation is somewhat easier, but once a knot or a portion of a knot is formed it must be pushed down to tighten the suture against the tissue. Simple knot pushers are available for this purpose as exemplified by U.S. Pat. Des. 359,355; Des. 386,583 and Des. 387,161 (all to Ferragamo et al.) and U.S. Pat. No. 2,595,086 (Larzelere), U.S. Pat. No. 4,602,635 (Mulhollan et al.), incorporated by reference herein.
Tightening a double or multiple knots which are initially formed extracorporeally and then pushed to the tissue site is shown in U.S. Pat. No. 4,961,741 (Hayhurst) and 5,084,058 (Li) as being accomplished by a relatively complex device which requires the suture legs to be threaded through the device to pre-form loose knots to be pushed. Another device known for this purpose utilizes a knot holding forceps and a cooperating knot pusher to tighten double or multiple knots as shown in U.S. Pat. No. 5,217,471 (Burkhart).
Intracorporeal knot formation is often accomplished simply with manual manipulation of suture within the workspace available through the use of forceps, graspers, snares and the like. Some instruments are known to assist in this manipulation by forming one of the suture legs into loops or twisting the legs together. For example, cannulated corkscrew devices facilitate such knot formation as exemplified by U.S. Pat. No. 4,641,652 (Hutterer et al.). Knot pushers may be used in these cases as well.
There is a continuing need to improve endoscopic knot formation to simplify the process. It is accordingly an object of this invention to provide an intracorporeal knot tier which can manipulate suture to facilitate the formation of knots at a work site.
It is another object of this invention to provide an intracorporeal knot tier by which a user can with one hand form a loop in a length of suture and then form a knot by passing through the loop the other end of the suture.